The present invention relates broadly to rotary lawn mowers and in particular to rotary mulching mowers.
A rotary mower may be generally defined as a mowing implement with a cutting blade mounted for rotation about a substantially vertical axis to define a generally horizontal rotary cutting path. Two basic types of rotary mowers can be characterized as bagging and mulching mowers. In the conventional bagging rotary mower, the objective is to collect the grass clippings as the grass is cut and remove substantially all of the grass clippings from the lawn. In the case of bagging mowers, the mower housing which defines the cutting chamber in which the blade is disposed, is designed to ingest and discharge significant amounts of air to carry suspended clippings into a collection device. The housing is streamlined in the cutting chamber region to provide adequate airflow to discharge and collect the clippings.
The objective of the mulching mower is contrary to bagging mower theory in that the mulching mower is designed to bury the grass clippings and other organic lawn debris deep into the lawn. The clippings are preferably disposed beneath the surface of the cut grass and therefore will not leave an unsightly deposit on the top of the lawn. Additionally, with the clippings near the ground where it would typically be relatively damp, micro-organisms will feed on the clippings and decompose the clippings. The clippings thus serve as a soil nutrient.
In mulching it is desirable to cut the clippings to as short a length as possible to ensure that the clippings are small enough to be driven beneath the surface of the lawn. It is also desirable to violently agitate the grass as it is being cut to again facilitate deposit of the clippings below the lawn surface. Mulching mowers generally provide a deep deck housing in which the clippings are suspended such that clippings may be cut several times before they are deposited into the cut path. Since the mulching mower is not designed with a specific air discharge port, the housing must be designed such that there is a balance between the air intake and air discharge. It has been found that the quality of cut will be dependent upon the air balance between intake and discharge from the mulcher cutting chamber.
The conventional prior art mulchers have encountered some difficulty in achieving optimum deposit of the grass clippings beneath the lawn surface when the lawn is cut with the grass relatively long or lush. Specifically, the conventional mulcher designs leave unsightly clippings on the top of the lawn under these conditions. The clippings may be deposited in windows along each side of the cut path of the mulching mower. In addition to having a displeasing aesthetic effect, the clippings that are left deposited on the lawn surface are not in the area where they can be decomposed to return nutrients to the soil. Therefore, with the prior art mulching mowers the operator must be extremely careful that he either continually cut the grass when it reaches a certain height or that each time he cuts he adjust the height of cut of the mower such that the clippings will be short enough to be deposited beneath the lawn surface. Under heavy growing conditions, much more frequent cutting of the lawn is required in the prior art mulching mowers.
It is desirable, therefore, to have a mulching mower that will perform under a variety of lawn conditions to include relatively long or lush grass. The present invention is such a rotary mulching mower that buries the clippings beneath the lawn surface even when the grass is relatively long and lush. This range of operation of the present invention is achieved in part by the provision of kickers or baffles within the cutting chamber that essentially disrupt the stream of grass clippings suspended therein and directs the clippings generally downward into the cut path and inward with respect to a substantially vertical rotational axis of the cutting blade. The kickers in combination with the housing and blade design thereby provide optimum clipping dispersion under varying lawn conditions. The housing of the rotary mulching mower of the present invention is also designed such that the air intake and air discharge are sufficiently balanced to improve the quality of cut and in addition to facilitate distribution of the clippings uniformly across the cut path of the mower.